the detroit 'green meanies' were two strokes, but whole different than saws,which are two cycle gasoline/spark ignited. DDA were diesel, oil in the crankcase, exhaust valves and cam on top, intake ports on the bottom of cylinders sort of like transfers on a saw. That required a positive Roots type blower to get air moving to start it, where a turbo would not work. The blower then pushed air in the bottom of cylinder and out the top, no fuel in the mix. Injected fuel near TDC for combustion.
Many of the later DDA had one or two exhaust driven turbos also.
In military and tank applicaitons, the engines were getting about 1 hp per cubic inch at 2500-3500 rpm. The 1957 injected vette at 1 hp/in3 was a really big deal. The DDA was getting that at one half the rpm's, for minutes or hours instead of seconds on the dyno, so was pretty awesome.
Big ship diesels (50,000 to 100,000 hp at maybe 100 to 250 rpm) still are pretty much the same principles, but the DDA two cycle is gone due to noise and pollution.